In rotary internal combustion enginges of the type that have a rotor that is divided into a compressor section and a power section that are in side-by-side relation, mounted on the same shaft and rotated together, it is desirable to have the compressed gas charge moved from the compressor section into the expansion pocket of the power rotor section in as expedient a manner as possible. It is further desirable that the expansion pocket be so constructive and arranged as to provide maximum moment as a result of rapid burning of the charge therein. In prior art devices of this type, the compressed gas charge often travels through a rather long path to the expansion pocket or there may be a substantial portion of this path or passage wherein this compressed gas charge is not effective to provide a moment for imparting rotation to the rotor. In the present invention, there is a very close working relation and communication between the working members of the rotary engine. The compressed gas charge is completely discharged from the compression section of the rotor laterally through an opening in the relatively thin separating plate and into the expansion pocket that is formed in the rotor power section. This expansion pocket is formed in a pivotal wing member, the outer extremity of which is in engagement with the inner peripheral wall of the stator of the rotary engine. This wing pivots outward into the expansion chamber formed between the rotor periphery and the inner periphery or peripheral wall of the stator, whereby maximum moment is applied during this expansion function.